1 files changed, 93 insertions, 0 deletions
diff --git a/indra/newview/app_settings/shaders/class1/deferred/aoUtil.glsl b/indra/newview/app_settings/shaders/class1/deferred/aoUtil.glsl
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+++ b/indra/newview/app_settings/shaders/class1/deferred/aoUtil.glsl
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+/** 
+ * @file class1/deferred/aoUtil.glsl
+ *
+ * $LicenseInfo:firstyear=2007&license=viewerlgpl$
+ * Second Life Viewer Source Code
+ * Copyright (C) 2007, Linden Research, Inc.
+ * 
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation;
+ * version 2.1 of the License only.
+ * 
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ * 
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+ * 
+ * Linden Research, Inc., 945 Battery Street, San Francisco, CA  94111  USA
+ * $/LicenseInfo$
+ */
+
+uniform sampler2D       noiseMap;
+
+uniform float ssao_radius;
+uniform float ssao_max_radius;
+uniform float ssao_factor;
+uniform float ssao_factor_inv;
+
+vec4 getPosition(vec2 pos_screen);
+
+vec2 getKern(int i)
+{
+    vec2 kern[8];
+    // exponentially (^2) distant occlusion samples spread around origin
+    kern[0] = vec2(-1.0, 0.0) * 0.125*0.125;
+    kern[1] = vec2(1.0, 0.0) * 0.250*0.250;
+    kern[2] = vec2(0.0, 1.0) * 0.375*0.375;
+    kern[3] = vec2(0.0, -1.0) * 0.500*0.500;
+    kern[4] = vec2(0.7071, 0.7071) * 0.625*0.625;
+    kern[5] = vec2(-0.7071, -0.7071) * 0.750*0.750;
+    kern[6] = vec2(-0.7071, 0.7071) * 0.875*0.875;
+    kern[7] = vec2(0.7071, -0.7071) * 1.000*1.000;
+       
+    return kern[i];
+}
+
+//calculate decreases in ambient lighting when crowded out (SSAO)
+float calcAmbientOcclusion(vec4 pos, vec3 norm, vec2 pos_screen)
+{
+    float ret = 1.0;
+    vec3 pos_world = pos.xyz;
+    vec2 noise_reflect = texture2D(noiseMap, pos_screen.xy/128.0).xy;
+        
+    float angle_hidden = 0.0;
+    float points = 0;
+        
+    float scale = min(ssao_radius / -pos_world.z, ssao_max_radius);
+    
+    // it was found that keeping # of samples a constant was the fastest, probably due to compiler optimizations (unrolling?)
+    for (int i = 0; i < 8; i++)
+    {
+        vec2 samppos_screen = pos_screen + scale * reflect(getKern(i), noise_reflect);
+        vec3 samppos_world = getPosition(samppos_screen).xyz; 
+        
+        vec3 diff = pos_world - samppos_world;
+        float dist2 = dot(diff, diff);
+            
+        // assume each sample corresponds to an occluding sphere with constant radius, constant x-sectional area
+        // --> solid angle shrinking by the square of distance
+        //radius is somewhat arbitrary, can approx with just some constant k * 1 / dist^2
+        //(k should vary inversely with # of samples, but this is taken care of later)
+        
+        float funky_val = (dot((samppos_world - 0.05*norm - pos_world), norm) > 0.0) ? 1.0 : 0.0;
+        angle_hidden = angle_hidden + funky_val * min(1.0/dist2, ssao_factor_inv);
+            
+        // 'blocked' samples (significantly closer to camera relative to pos_world) are "no data", not "no occlusion" 
+        float diffz_val = (diff.z > -1.0) ? 1.0 : 0.0;
+        points = points + diffz_val;
+    }
+        
+    angle_hidden = min(ssao_factor*angle_hidden/points, 1.0);
+    
+    float points_val = (points > 0.0) ? 1.0 : 0.0;
+    ret = (1.0 - (points_val * angle_hidden));
+
+    ret = max(ret, 0.0);
+    return min(ret, 1.0);
+}
+